Seals are common mechanical devices used when it is desired to prevent flow of fluid through a given space. One type of seal, referred to as a brush seal, uses a plurality of bristles held in place across the area to be sealed. An advantage of a brush seal is its inherent ability to move and yet maintain a seal as surfaces forming the area to be sealed are moving themselves.
One environment in which brush seals are commonly used is within gas turbine engines of the type used for providing propulsion to aircraft, auxiliary power to aircraft or other moving vessels, or in land based power generation situations. Brush seals used within gas turbine engines are used to prevent leakage of working medium air out of the main flow path of the engine. Minimization of such leakage is important since any leakage degrades the efficiency of the engine thereby increasing the fuel consumption of the engine and cost of operation of the engine. Moreover, pressurized air or combustion gases which escape from the main flow path of the engine are at elevated temperatures and may contact engine components having limited tolerance for such temperatures. For example, the brush seal may be used between a gap formed between a stationary part such as a diffuser, engine casing or stator, and a rotating part, such as a turbine blade, shaft, or rotor.
While effective, it is nonetheless necessary to replace such brush seals over time. For example, such replacement may be scheduled after a given number of hours of operation. However, conventionally manufactured brush seals are welded assemblies, which necessarily make removal difficult. In addition, as the components forming the brush assembly are welded together, replacement of individual components comprising the assembly is not possible. As a result, the entire assembly needs to be replaced at significant cost, not only in terms of material but in labor and down time of the engine as well.
Recently, it has been known to manufacture brush seals using clips or fasteners to hold the assembly together. These two are effective, but require additional machining under relatively close tolerances, thus increasing the cost of production.